This invention relates to a paper money discriminator for identifying the type of a bank note by detecting colors thereof from reflected or transmitted light obtained by irradiating the bank note.
Generally, a paper money discriminator identifies printed patterns and the like formed on a bank note by detecting colors thereof from reflected or transmitted light obtained by irradiating the bank note, thereby identifying the type of the bank note or judging whether the bank note is genuine or counterfeit.
Japanese Patent Publication No. 39435/1972 and Japanese Patent Public Disclosure No. 84695/1976 disclose a type of paper money discriminator which has a plurality of light sources capable of irradiating the surface of a bank note from positions thereabove, and a plurality of color detecting sensors for receiving, through color filters, reflected or transmitted light traveling by way of the bank note, the plurality of color detecting sensors being disposed close to the bank note.
However, in this type of paper money discriminator, the spaces in which the light sources and the color detecting sensors are disposed are comparatively large, and, if the area of irradiation and/or the number of color detecting sensors are increased, these light sources and color detecting sensors are concentrated in a limited inspection space, and the disposition of the light sources and the sensors is respectively restricted. For this reason, the construction of this type of discriminator tends to be complicated.
A type of bank note discriminator such as the one disclosed in Japanese Patent Public Disclosure No. 6597/1976 has previously been known in which a type, of bank note is identified on the basis of a brightness pattern detected from reflected or transmitted light obtained by irradiating the bank note.
The above-mentioned Japanese Patent Public Disclosure No. 84695/1976 discloses an example of another type of bank note discriminator in which reflected or transmitted light obtained by irradiating a bank note is detected after being separated into lights of two different wavelengths (red light and infrared light) and the bank note is judged to be genuine or counterfeit on the basis of the ratio of outputs from detected light or the difference between the same.
The identification of the type of bank note and/or the discrimination of a real one from a counterfeit is carried out by combining the outside dimensions or magnetic patterns with the above types of optical pattern or color discrimination.
The manner of discrimination in the first of the above-described conventional systems is based on a so-called method of using monochrome densities, and thus it cannot even recognize the difference between a bank note and a counterfeit note (monochromic copy).
The latter is capable of discriminating a bank note from a color-copy counterfeit or a color-printed counterfeit but incapable of identifying the type of bank note. An additional means of identification is therefore required.